Decreasing the permeability and producing subterranean formations

ABSTRACT

A method for decreasing the permeability and producing a subterranean formation by injecting starch granules into the formation and thereafter increasing the temperature of the granules within the formation to a temperature at which at least a portion of the starch granules are caused to increase to a size greater than their size before heating.

United States Patent IWI Marx [ 1 Oct.2, 1973 DECREASING THE PERMEABILITY AND PRODUCING SUBTERRANEAN FORMATIONS [75] Inventor: John W. Marx, Bartlesville, Okla.

[73] Assignee: Phillips Petroleum Company, Bartlesville, Okla.

22 Filed: Oct. 21, 1971 21 Appl. No.: 191,188

[52] U.S. Cl 166/272, 166/292, 166/294 [Sl] Int. Cl E2ld 43/24 [58] Field of Search 61/36 A, 36 R;

[56] References Cited UNITED STATES PATENTS 5/1943 Van Leeuwen 61/36 R OTHER PUBLICATIONS Hawley, The Condensed Chemical Dictionary, 197 l P.

Rogers, Composition and Properties of Oil Well Drilling Fluids, 1963, P. 414.

Primary ExaminerMarvin A. Champion Assistant Examiner-Jack E. Ebel Att0rneyYoung and Quigg [57] ABSTRACT A method for decreasing the permeability and producing a subterranean formation by injecting starch gran: ules into the formation and thereafter increasing the temperature of the granules within the formation to a temperature at which at least a portion of the starch granules are caused to increase to a size greater than their size before heating.

15 Claims, 2 Drawing Figures PATENTEUBCT 2 3.762.475

OOOOOOOOOOOOOO INVENTOR.

ATTORNEYS DECREASING THE PERMEABILITY AND PRODUCING SUBTERRANEAN FORMATIONS It is desirable to provide a method for effectively plugging portions of subterranean hydrocarbon conbecause it has the smallest average particle size (typically about 4.5 microns) and the most narrow size distribution (typically 3-6 microns) of any natural starch. When starting with these small, essentially uniform partaining formations and to provide a method for produc- 5 tieles, an operator can accommodate a wide variety of ing hydrocarbons from the formation. Further, it is also permeability situations or differences by control of desirable to provide a method whereby the portion of swelling conditions. hygroczgbon fi sfi gzggsg gg The starch granules are mixed with a carrier fluid and h an a viscous 00 mg ma 6 l0 injected into and through the well bore to a location t i v mien resides in pectin Starch within the formation 2. The preferred mixture for inn m e J g jecting the starch granules into the formation comgranules into the formation and thereafter increasing prises about 1,000 to about 5,000 parts per mllllOl'l the temperature of, the granules to a temperature at starch granules m brine having greater than about which at least a portion of the starch granules are 50,000 parts per mllllOIl NaCl. With less starch grancaused to increase to a size at least greater than their ules the formation ores are n t H f t size before heating. Hydrocarbons can be produced fined b th t I l 5 655) from the formation by a secondary recovery means and arts g f th a a an a gtrea t the temperature of at least a portion of the granules can b :M i 0 ti li s g lago hear thereafter be heated to a temperature in excess of a N gl b P b a out k hparts P r: about 95 C. for dissolving a portion of the granules ml a J S f f attac k thereby forming a viscous flooding material. gganu es an re uce t err e ectlveness, as nown in Other aspects, objects, and advantages of the present t e invention will become apparent from a study of the dis- T e volume of the mixture injected into the formaclosure, the appended claims, and the drawings. tion is dependent upon the thickness of the formation The drawings are diagrammatic views of well bores desired to be plugged,'the permeability, severity of tinand a subterranean formation upon which the methods gering, and other factors known in the art. In practice, of this invention are practiced. however, it is preferred that a slug of the first material FIG. 1 shows the hydrocarbon-containing formation, being about 100 to about 500 barrels of mixture per well bores penetrating said formation, and the plugging foot of thickness desired to be selectively plugged of this invention and should be initially injected. As is also known in the art,

FIG. 2 shows forming of the viscous material in the the further the slug is desired to be positioned laterally formation. from the well bore, the greater the volume of mixture Referring to FIG. 1, a subterranean hydrocarbon that h ld b injgcted, gzf il l??? th a first 3 2 32 5 2 232 35 After the starch granules have been injected into the 2 f er fi g g g z i g to formation and moved to their desired location relative examp e I p y p to the well bore, the temperature of the granules within duction well 8 and an in ection well 10 spaced from l the formation 4, for example, is increased to a temperasaid production well 8. The wells can be open completure at Wl'llCl'l at least a portion of the starch granules, trons, cased through, or of other types known in the art 40 preferably substantially all of the starch granules of the and can have tubing hung in the wells or set through k ui ed in other manners as known in the first in ected mlxture, are caused to increase to a size 2?: ers or eq pp greater than their size prior to heating.

This invention is particularly useful in secondary re- The size increase of the starch granules relative to the covery projects to prevent fingering with resultant early amount of heating and the salt content of the mixture breakthrough of the flooding medium to the produccan easily be determined by one skilled in the art. The lion but it Should be understood that the pl gfollowing is example data for rice starch granules:

m Initial Terminal particle size after heating (microns) particles 0 NaCl content (wt. percent) (microns) C. C. C. C. C. C. C.

ging method can be utilized for plugging of the subter- A eat r th ab t 95 C d to a l r extent ranean formation for any purpose. 55 at lower temperatures, there is some conversion of In the method of this invent Starch granules, P starch to soluble starch hereafter referred to generally erably having a size in the range of about 5 to about 32 as di l i f h starch gramiios microns, are injected into the formation 2. It has been B h i i f h i f h Starch granules found that if the largest particles of the injected starch hil id Starch gramuos are i i d i hi h granules have sizes within the range Of about IO 60 pore spaces of the formation 4, the pore paces are about times a medium P of the forfhahoh caused to be plugged with the starch granules tightly P0rtioh desh'ed to he Plugged, that Sam matenal h wedged into the pore spaces and thereby substantially more efhclehtly fill the p Spaces to a greater rad'al completely sealing the pore spaces and maintaining the distance from the well bore through which injected, for granules against dislocation th f example the injection 65 The preferred heating medium is steam, however Starch granules that can be utilized with the method of this invention are, for example, of the following starch types: rice, corn, wheat, tapioca, sago, arrowroot, barley, and potato, among others. Rice starch is the preferred starting material for use in this invention other heated fluids can be utilized. The rate of injection of the mixture is dependent upon manyfactors and the selectivity that is desired. This rate is easily determined by one skilled in the art from injectivity profile logging, core analysis and other means. As is known, the mixture will pass into the channels and fingers which offer the path of least resistance and which zone it is desirable to plug to establish a more complete flood front sweep if the rate of injection is not excessive for that particular formation.

FIG. 1 shows a steam flood wherein a channel 12 and accompanying fingers 14, 16 through a first formation portion 4 have had the starch granules l8 injected thereinto and heated to their enlarged condition as described above. The channel 12 and fingers 14, 16 are thereby selectively plugged and subsequent injection of the steam, for example, into the formation 2 through the injection well causes hydrocarbons to pass through the formation 2 and into the production well 8 for recovery to the surface.

Referring to FIG. 2, as the steam front 20 moves through the formation 2, the temperature behind the steam front increases to a temperature in excess of about 95 C. This increase causes a portion of the starch granules to dissolve and form a viscous material 22 in the condensate water of the formation portion of 4. Continued injection moves this viscous material 22 through the formation thereby further sweeping hydrocarbons from the formation.

Where the heating medium is not steam, the temperature of injected fluid can be increased to form the viscous material 22.

As new channels and fingers develop, other slugs of the starch granules can be intermittently injected into the formation to plug the formation as described above.

By the methods of this invention, more uniform and greater sweep efficiences can be obtained, thereby avoiding the loss of valuable hydrocarbons by the bypassing of said hydrocarbons by the flood fronts. The method of this invention can also be utilized to selectively plug a gas cap and prevent the entry of water encroachment by plugging the formation adjacent a producing well.

Other modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion and accompanying drawing,

be unduly limited thereto.

What is claimed is:

trated by at least one injection well and at least one production well spaced from said injection well, comprising:

injecting a carrier fluid having starch granules into the formation, the largest of said starch granules being of a size in the range of about 1.1 to about 2.5 times a median pore size of the formation;

increasing the temperature of the formation to a temperature in the range from that temperature at which at least a portion of the starch granules in the formation are caused to increase in size to an upper temperature of about 95 C.;

injecting fluid into the injection well and outwardly through the formation; and

producing fluids entering the production well.

6. A method, as set forth in claim 5, wherein the starch granules injected are of a size in the range of about 5 to about 32 microns.

7. A method, as set forth in claim 5, wherein the starch granules are dispersed in a carrier fluid comprising brine.

8. A method, as set forth in claim 5, wherein the starch granules are granules of rice starch.

9. A method, as set forth in claim 5, wherein heated fluid is injected into the formation for increasing the size of the starch granules; and

continuing to inject heated fluid into the formation for moving hydrocarbons into the producing well.

10. A method, as set forth in claim 9, further including intermittently injecting other slugs of starch gran- 1. A method for decreasing the permeability of a subterranean hydrocarbon containing formation penetrated by at least one well bore and producing hydrocarbons from the formation, comprising:

injecting a carrier fluid having starch granules downwardly through the well and into the formation, the largest of said starch granules being of a size in the range of about 1.1 to about 2.5 times a median pore size of the formation; increasing the temperature of the granules within the formation to a temperature in the range from that temperature at which at least a portion of the starch granules are caused to increase in size to an upper temperature of about 95 C.; and thereafter producing fluids entering the well bore. 2. A method, as set forth in claim 1, wherein the starch granules injected are of a size in the range of about 5 to about 32 microns.

3. A method, as set forth in claim 1, wherein the starch granules are dispersed in a carrier fluid comprising brine.

4. A method, as set forth in claim 1, wherein the starch granules are granules of rice starch.

5. A method for producing hydrocarbons from a subterranean hydrocarbon containing formation peneules into the formation during the injection of fluid into and through the formation for moving hydrocarbons into the production well.

11. A method, as set forth in claim 9, including increasing the temperature of a portion of the enlarged starch granules in the formation to a temperature greater than about C. for converting at least a portion of the starch granules to soluble starch.

12. A method for producing hydrocarbons from a subterranean hydrocarbon containing formation penetrated by at least one injection well and at least one producing well spaced from said injection well, comprising:

Step 1 injecting a carrier fluid having starch granules down the injection well and into the formation, the largest of said starch granules being of a size in the range of about 1.1 to about 2.5 times a median pore size of the hydrocarbon containing formation;

Step 2 injecting heated fluid downwardly through the injection well and outwardly through the formation into contact with the starch granules to heat the granules to a temperature in the range from that temperature at which at least a portion of the starch granules in the formation are caused to increase in size to an upper temperature of about 95 C. to alter the permeability of the formation;

Step 3 continuing to inject heated fluid through the formation to move a flood front and hydrocarbons through the formation toward the producing well and heat the starch granules to a temperature greater than 95 C.; and

Step 4 producing fluids entering the producing well.

13. A method, as set forth in claim 12, including adding at least one other volume of starch granules to the injected fluid of Step 3.

14. A method, as set forth in claim 12, wherein the heated fluid is steam.

15. A method, as set forth in claim 14, wherein the starch granules are dispersed in a carrier fluid comprising brine.

*' t i i UNITED S'ETATES PA'EENT OFFlQE CERTl-FIGATE 0F (IORREQTEON Patent NO. 3,762,475 Dated October 2, 1973 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 50, delete "outwardly through" and insert into Signed and sealed this 2nd day of April 1974 (SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050(10-69) USCOMWDC i 0.5. GOVERNMENT PRINTING OFFICE: I959 0-366-33L 

2. A method, as set forth in claim 1, wherein the starch granules injected are of a size in the range of about 5 to about 32 microns.
 3. A method, as set forth in claim 1, wherein the starch granules are dispersed in a carrier fluid comprising brine.
 4. A method, as set forth in claim 1, wherein the starch granules are granules of rice starch.
 5. A method for producing hydrocarbons from a subterranean hydrocarbon containing formation penetrated by at least one injection well and at least one production well spaced from said injection well, comprising: injecting a carrier fluid having starch granules into the formation, the largest of said starch granules being of a size in the range of about 1.1 to about 2.5 times a median pore size of the formation; increasing the temperature of the formation to a temperature in the range from that temperature at which at least a portion of the starch granules in the formation are caused to increase in size to an upper temperature of about 95* C.; injecting fluid into the injection well and outwardly through the formation; and producing fluids entering the production well.
 6. A method, as set forth in claim 5, wherein the starch granules injected are of a size in the range of about 5 to about 32 microns.
 7. A method, as set forth in claim 5, wherein the starch granules are dispersed in a carrier fluid comprising brine.
 8. A method, as set forth in claim 5, wherein the starch granules are granules of rice starch.
 9. A method, as set forth in claim 5, wherein heated fluid is injected into the formation for increasing the size of the starch granules; and continuing to inject heated fluid Into the formation for moving hydrocarbons into the producing well.
 10. A method, as set forth in claim 9, further including intermittently injecting other slugs of starch granules into the formation during the injection of fluid into and through the formation for moving hydrocarbons into the production well.
 11. A method, as set forth in claim 9, including increasing the temperature of a portion of the enlarged starch granules in the formation to a temperature greater than about 95* C. for converting at least a portion of the starch granules to soluble starch.
 12. A method for producing hydrocarbons from a subterranean hydrocarbon containing formation penetrated by at least one injection well and at least one producing well spaced from said injection well, comprising: Step 1 - injecting a carrier fluid having starch granules down the injection well and into the formation, the largest of said starch granules being of a size in the range of about 1.1 to about 2.5 times a median pore size of the hydrocarbon containing formation; Step 2 - injecting heated fluid downwardly through the injection well and outwardly through the formation into contact with the starch granules to heat the granules to a temperature in the range from that temperature at which at least a portion of the starch granules in the formation are caused to increase in size to an upper temperature of about 95* C. to alter the permeability of the formation; Step 3 - continuing to inject heated fluid through the formation to move a flood front and hydrocarbons through the formation toward the producing well and heat the starch granules to a temperature greater than 95* C.; and Step 4 - producing fluids entering the producing well.
 13. A method, as set forth in claim 12, including adding at least one other volume of starch granules to the injected fluid of Step
 3. 14. A method, as set forth in claim 12, wherein the heated fluid is steam.
 15. A method, as set forth in claim 14, wherein the starch granules are dispersed in a carrier fluid comprising brine. 